Low-viscosity nonaqueous liquid pigment dispersions and methods of utilizing such compositions

ABSTRACT

A new and useful nonaqueous liquid pigment dispersion is provided which is easy to handle and produces thorough and effective colorations within target media, particularly as compared to standard solid pigments or high-viscosity liquid pigment dispersions. More specifically, the present invention relates to liquid pigment dispersions possessing viscosities of at most 5,000 centipoise at standard temperature and pressure. Such a low viscosity is obtained through the addition of relatively low amounts of aprotic viscosity modifiers possessing dipole moments of at between about 1.0 and 5.0, alternatively measured in terms of a flash point between about −20° C. and 180°, such as, most preferably cyclic carbonates. The resultant low-viscosity pigment compositions thus can be incorporated into any standard pigment-coloring method (such as, for example, polyurethane, polyolefin, and the like) without the problems associated with traditionally utilized solid or thickened, high viscosity pigment materials. The method of coloring such target media is also encompassed within this invention.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of co-pending application09/586,391, filed on Jun. 2, 2000.

FIELD OF THE INVENTION

[0002] This invention relates to new and useful nonaqueous liquidpigment dispersions which are easy to handle and produce thorough andeffective colorations within target media, particularly as compared tostandard solid pigments or high-viscosity liquid pigment dispersions.More specifically, the present invention relates to liquid pigmentdispersions possessing viscosities of at most 5,000 centipoise atstandard temperature and pressure. Such a low viscosity is obtainedthrough the addition of relatively low amounts of aprotic viscositymodifiers possessing dipole moments of between about 1.0 and 5.0, or,alternatively, a flash point of between about −20° C. and 180° C., suchas, most preferably, cyclic carbonates. The resultant low-viscositypigment compositions thus can be incorporated into any standard coloringmethod utilizing pigments (such as, for example, for polyurethanes,polyolefins, and the like) without the problems associated withtraditionally utilized solid or thickened, high viscosity pigmentmaterials. The method of coloring such target media is also encompassedwithin this invention.

BACKGROUND OF THE PRIOR ART

[0003] Polyurethane products, such as foams, resins, and the like, havetraditionally been colored by pigments, polymeric colorants, and dyes.Generally, these colorations are performed in situ during foam, resin,etc., formation. For instance, polymeric colorants (i.e.,polyoxyalkylenated colorants), such as those described in U.S. Pat. No.4,284,279 to Cross et al., have been introduced within polyolcompositions during slabstock foam production. The “colored” polyol thenreacts with an isocyanate composition, in the presence of a catalystpossibly, to form the desired colored foam. Pigments have also beenadded in the past, most notably in solid, paste, or powder form, to apolyol stream to form the same type of colored foam products. Suchcompounds are readily available and inexpensive; however, they alsoexhibit or create problems during handling, mixing (with other pigmentsto create different shades, for example), and actual incorporationwithin target media. Furthermore, pigments, being solid in nature, tendto from clumps of solids within target media that leads to aestheticallydispleasing consequences or clogging of machinery or instrumentation(such as pumps, valves, injectors, and the like). Additionally, spillsare likely (since the powder or solid form of such pigments do nottransport easily due to atmospheric conditions and possible airdisturbances), and clothes or hand staining by difficult-to-handlepigment compounds is very likely to occur through the utilization ofsuch solid coloring agents. As such, there is a need to improve uponthese handling deficiencies of standard solid and powder pigmentscompounds. Polymeric colorants, being liquid in nature, have proveneasier to use in such processes due to facilitation of handling,particularly at industrial levels. Low viscosity dispersions of pigmentswith low color availability have been developed within this industry asan attempt to alleviate such handling problems (and thus permitutilization of polymeric colorant-like liquid compositions). However,such low viscosity dispersions are not storage stable and haveprecipitation problems that produce uneven colorations within the finalpolyurethane product and thus make such dispersions unsuitable forlarge-scale industrial use as well. Traditionally, a trade-off has beenpresent with pigments: the higher the viscosity of the pigment solution,the better the storage stability; the lower the viscosity, the worse thestorage stability. As such, there is a recognized need to provide animproved pigment dispersion that possesses long-term storage stabilityas well as good colorability of the target polyurethane composition.Furthermore, such dispersions should exhibit the shade general degree ofcolor depth within the target article substrate as a standard pigmentprovides. To date, there have existed no such needed advancements inthis art.

OBJECTS OF THE INVENTION

[0004] It is therefore an object of this invention to provide asubstantially uniform, low viscosity liquid pigment dispersion for easeof handling in large industrial applications. A further object is toprovide a liquid pigment dispersion for utilization within a coloredfoam production process. A further objective of this invention is toprovide a storage-stable pigment dispersion that retains the samegeneral color value as the non-dispersed pigment.

SUMMARY OF THE INVENTION

[0005] Accordingly, this invention is directed to a nonaqueous liquiddispersion comprising at least one pigment and at least one aproticviscosity modifying compound exhibiting a dipole moment of between about1.0 and 5.0 or alternatively, a flash point of between about −20° C. and180° C. Also encompassed within this invention is a method of producinga colored polyurethane comprising the steps of

[0006] (a) providing a polyol composition;

[0007] (b) introducing a nonaqueous liquid dispersion comprising atleast one pigment and at least one aprotic viscosity modifying compoundexhibiting a dipole moment of at least 1.0. into said polyol compositionto form a colored polyol composition; and

[0008] (c) mixing said colored polyol composition with an isocyanate toform a polyurethane.

[0009] The term “nonaqueous” denotes a composition into which no waterhas been specifically introduced. Due to the possibility of atmosphericwater being introduced through exposure to a relatively humidenvironment, this term does not rule out the potential for any water tobe present through such a manner. The term “liquid dispersion” isintended to encompass any composition which is present in a fluid state(i.e., possessing a viscosity of below about 10,000 centipoise atstandard temperature and pressure). The term “aprotic” is well knownwithin the chemical arts and simply means that no protons can beaccepted or donated by the specific compound. As such, it is imperativethat certain moieties not be present on the intended viscosity modifyingcompound. Such unwanted moieties include, without limitation, acidgroups, hydroxyls, amines, and the like. However, as noted above, thislist is not definitive; any aprotic compound possessing the requireddipole moment or flash point is included in this definition.

[0010] The dipole moment requirement for the viscosity modifyingcompound is necessary to provide the desired performance characteristicsfor the inventive nonaqueous pigment-containing dispersion. It has beenfound, surprisingly, that the selection of a relatively low dipolemoment viscosity modifying compound provides the desired drasticlowering of overall viscosity while simultaneously separating individualpigment particles within solution, and preventing reagglomeration of thesame particles. Furthermore, due to the low dipole moment, thecorresponding flash point of the viscosity modifying compound is alsorelatively low in order to permit removal of such a compound uponintroduction within a coloring method utilizing relatively lowprocessing temperatures, if desired. Alternatively, such compounds mayalso react within the target media as well. As such, since the aproticcompound must exhibit a low flash point, and dipole moments have notbeen recorded for all compounds which may function in this capacitywithin the inventive dispersions, the viscosity modifying compound mayalternatively be defined in relation to its aprotic nature and its flashpoint. Thus, a flash point of between about −20° C. and 180° C. isnecessary; preferably such a level is between 0° C. and 165° C.; morepreferably from 80° C. to about 160° C.; most preferably between about95° C. and 145° C. Such an aprotic compound thus does not affect anyproduction methods (such as, as merely one example, polyurethanecoloring through initial introduction within a polyol compositionfollowed by admixing with an isocyanate; at low heat exposures, theviscosity modifying compound will evaporate from the final compositionwith relative ease). It is also preferable that the selected aproticviscosity modifying compound (or compounds) be liquid in nature andexhibit a viscosity of at most 500 centipoise at standard temperatureand pressure (i.e., 25° C. at 1 atmosphere) as measured by a BrookfieldViscometer. This requirement facilitates handling (particularly inlarge-scale industrial applications) and more easily permits productionof the desired viscosity level for the nonaqueous liquid pigmentdispersion itself.

[0011] Also determined to be of great importance to the selection of aproper viscosity modifying compound within the inventive nonaqueousliquid pigment dispersion is the molecular weight of such a compound.Due to the low dipole moment (which concerns the low polarity of thecompound itself), and/or the low flash point necessary for such acompound, the molecular weight must also be rather low. Thus, amolecular weight of at most 200 is available for the inventivedispersion; preferably, this weight is at most 150; more preferably, atmost about 120; and most preferably, between about 85 and 116.

[0012] Such an inventive dispersion is preferably storage stable. Bythis term, it is intended that the inventive dispersion will remain in afluid state with substantially no precipitation or reagglomeration ofpigment for at least 60 days while being continuously exposed to atemperature of at least 50° C. Such a test is one manner of reproducinglong-term storage conditions and thus is not intended as being the solelimitation of temperature within this invention. One of ordinary skillin this art would appreciate the need to provide a modified test of thisnature. Thus, the inventive dispersions must merely exhibitsubstantially no precipitation and retention of its fluid state (lowviscosity) after exposure to high temperature storage for 60 days.

[0013] As noted above, the problems associated with pigments on anindustrial scale are remedied through the utilization of low viscositydispersions. Most mechanisms required to incorporate pigments orpigments dispersions within target media (for example, mixheads and/orfeed tank pipes for adding pigments within polyurethane foam productionmethods utilize certain pumps and feed lines that are highly sensitiveto pressure provided by high viscosity pigment formulations. With lowerand possibly more uniform viscosities between utilized pigmentcompositions, versatility of colors increases, thereby providing anoverall improved ability to produce desirable end products. Such lowviscosity may be (and has been) provided through the introduction of asolvent or viscosity modifier at a point in time near to the actualincorporation of the dispersion within the target media (forpolyurethane, the addition would take place either within the polyolcomponent or within the isocyanate component; the two components aremixed together with catalysts to form the desired polyurethane foam).However, this late introduction adds to the complexity and potentialproblems facing the user in producing such dispersions, again, andparticularly, at the industrial level. Thus, a storage stable, lowviscosity pigment dispersion is highly desired; unfortunately, suchdispersions have not been available until this recent development.

[0014] The inventive liquid dispersions exhibit a number of surprisingcharacteristics that lend themselves to a suitable inexpensive, yethighly effective coloring formulation, particularly for polyurethanes.Storage stability, without any appreciable precipitation of the pigmentsfrom solution, is of utmost importance with such dispersions. Theretention of extremely low viscosities, without any noticeableprecipitation, over a long duration, thus provides a highly desired,easy-to-handle product. Without intending to be bound to any scientifictheory, it is believed that such storage stability is provided throughthe interaction of the specifically selected aprotic viscosity modifierswith the target pigment particles while in dispersion. Such modifiersappear to reduce the size of any agglomerated pigment particles (fromlarger clumps to smaller particles), possibly through hydrogen bonding,initially, and subsequently prevent re-agglomeration by apparentlysurrounding the target small particles. Even upon heat exposure andcentrifugation, the viscosity of the inventive dispersion does notappreciably change. Additionally, the polyurethane foams produced withsuch inventive dispersions do not exhibit any appreciable losses incolor or shade depth in comparison with standard non-modified pigmentdispersions. Other impressive similarities between such viscositymodified and non-viscosity modified pigment dispersions are discussed ingreater detail below. Succinctly, the inventive dispersions provideimproved processability over non-modified pigment dispersions, as wellas simultaneous storage stability, all without any appreciable loss inperformance as compared with the same non-modified pigment dispersions.Such highly unexpected benefits are of enormous importance to improvingupon the available process conditions for applications requiring pigmentand/or pigment dispersion utilization.

[0015] The viscosity modifiers utilized within this invention must thusbe able to actually lower the viscosity of the target pigmentdispersions, be able to provide retention of such low viscosities uponlong-term storage, must not deleteriously affect the coloring ability ofthe pigments within the target media, most preferably polyurethane, andmust be easily removable from the target media or composition utilizedto produce or color such target media at a selected time, or, again,must react within such a target media or media-producing or -coloringcomposition. The above-discussed ability of the viscosity modifiers toreduce and retain small pigment particle size in the dispersion actuallyappears to provide more effective colorations throughout the targetmedia. Again, without intending to be limited to one specific scientificexplanation or theory, it is believed that by reducing particle size ina stable formulation allows for a more even coloring due to the greateruniformity of pigment size and distribution within the targetcomposition or article. Furthermore, the desired viscosity modifiers ofthe inventive dispersions must not deleteriously affect the actualtarget media itself. Preferably, the low dipole moment (and thus lowflash point) compounds can be easily evaporated from the target media(such as polyurethane) or the composition utilized to produce suchtarget media, or may react within the target media. Alternatively, ifevaporation is not followed (since, for example, heat exposure maydeleteriously effect the media itself), the selected compounds wouldactually be capable of reacting within the target media and enhancing,rather than harming, the characteristics of the target media uponintroduction within the pigment dispersion.

[0016] With all this in mind, it has been found that certain cycliccompounds, namely and preferably carbonates and lactones, provide thenecessary characteristics of the inventive pigment dispersion andexhibit the required low dipole moments. Preferably such viscositymodifiers are alkylene carbonates or butyrolactone; most preferably themodifier is selected from propylene carbonate, butyrolactone, andmixtures thereof. Other modifiers which may be present include DMSO(dimethylsulfoxide), valerolactones (both gamma and sigma types),1,3-dioxolane, caprolactone, tetrahydrofuran, and the like. Theextremely low flash points of 1,3-dioxolane and tetrahydrofuran makethem less appealing candidates for selection within this invention;however, their viscosity reducing abilities may be utilized in lowtemperature processes to produce the desired nonaqueous liquid pigmentdispersions. The viscosity modifier (or modifiers) may be present in anyamount that provides any reduction in viscosity of the target pigmentdispersion. Thus, any amount from about 0.01 to about 25% by weight ofthe total dispersion is possible; preferably, this amount is from about1 to about 15% by weight; more preferably from about 5 to about 10% byweight.

[0017] The use of cyclic carbonates and cyclic lactones in polyurethanechemistry is known. U.S. Pat. No. 3,883,466 describes the use of acyclic alkylene carbonate as a liquid modifier to moderate the reactionexotherm between the hydroxy component and the polyisocyanate in theproduction of a rigid, dense rapid-setting polyurethane. U.S. Pat. Nos.4,709,002 and 4,731,427 describe the use of cyclic alkylene carbonatesin the production of rigid RIM polyisocyanurate and urethane-modifiedpolyisocyanurate parts. These two references do not indicate why cyclicalkylene carbonate is used but do suggest that the carbonate can beadded to the isocyanate stream in order to reduce its viscosity. U.S.Pat. Nos. 5,028,635 and 5,149,458 report two polyurea-cyclic carbonateRIM systems having improved flow properties. European Patent 0,350,644and U.S. Pat. No. 5,442,034 report similar applications for cycliccarbonate in RIM elastomers and spray polyurea elastomers, respectively.U.S. Pat. No. 4,812,523 describes high solids thermosetting coatingcomposition with cyclic carbonates as reactive diluents to reduceviscosity. Cyclic carbonates and cyclic lactones have also been used asviscosity reducing agents in aromatic polyester polyols and polyetherpolyols (EP 0,276,452). No teachings or fair suggestions exist, however,that cover the incorporation, addition, etc., of such viscosity reducingagents to already liquid pigment dispersions to improve the desiredcoloring procedures.

[0018] Any standard pigment may be utilized within this inventivedispersion. Thus, carbon black, lamp black, titanium dioxide,phthalocyanine, and the like, may be present. Preferably, the pigmentexhibits an individual particle size of between about 13 and 75nanometers (in order to effectuate a reduction to and retention of thelowest possible agglomerate size). More preferably, then the pigment isa carbon black with a particle size of below about 30 nanometers. Thepreferred pigment may also be admixed with the viscosity modifier as asolution itself; the only requirement is that the overall viscosity ofsuch a pigment solution be reduced upon introduction of the desiredmodifier. Most preferred are the following specific pigments: SuperBlack 34-81107 (from Ferro), Black 34-88111 (from Ferro), Ester Black33-88033 (from Ferro), Carbon Black 1106 (from Rebus), Black 2101 (fromRebus), High Strength Black 2125 (from Rebus), Polyton Black UE-3012(from Dainippon Ink & Chemicals, Inc.), Union Black 5U-500 (from UnionChemical Ind., Ltd. of Taiwan), Union Black 3U-600, Ester Black ES 100(from PEKA), Pigment Black (from Dong Ryung of South Korea), Lung Black(from Kuang of Taiwan), Green 1750 (from Rebus), and Blue, Green, andBlack Pigment Dispersions from Ryvec. Certain pigments exhibit properviscosity reductions when admixed with certain viscosity modifiers notedwithin the low dipole moment class of compounds discussed previously.However, not every low dipole moment compound will produce the same typeor level of viscosity modification as desired. For instance, some of thelisted viscosity modifiers actually increase the pigment dispersionviscosity and thus are not proper selections on a commercial level.However, these compounds are still effective for other types of pigmentsand thus are included within the class of modifiers as listed above. Theproper selection for commercial practice of certain viscosity modifiersin tandem with certain pigment dispersions is a relatively simpleprocedure. In order to produce a commercially viable inventivenonaqueous liquid pigment dispersions, one of ordinary skill in the artmust analyze a physical mixture of the desired pigment and the lowdipole moment viscosity modifying compound(s); if the viscosity does notdecrease upon the introduction of 15% by weight of the modifier (incomparison with the total weight of the pigment), then the dispersionshould not be utilized at the commercial level. Again, this limit oncommercial activity solely pertains to that limited area; the inventivedispersions are not limited in scope due to that selection criteria.

[0019] Although the inventive dispersions may comprise a formulation ofsolely pigment (or mixtures of pigments) and viscosity modifier, otherconstituents may also be present. Such components include, withoutlimitation, solvents, such as water, lower alcohols, methyl ethylketone, and the like; other types of colorants, including dyes,polymeric colorants, inks, and the like; hydrotropes; salts; pHmodifiers; and surfactants.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] For the following examples, the particularly analyzed, and thuspotentially preferred aprotic viscosity modifying compounds (as well assome comparative compounds) were:

Viscosity Modifiers Tested

[0021] Dipole Modifier Moment Flash Point (° C.) Mol. Weight PropyleneCarbonate (PC) 4.9 135 102 Butylene Carbonate (BC) * 135 116 EthyleneCarbonate (EC) 4.87 160 88 Butyrolactone (BLO) 4.27 98 86 Caprolactone(CLO) 4.35 109 114 1,3-Dioxolane (DOL) 1.19 1 74 Tetrahydrofuran (THF)1.75 −17 72 Dimethylsulfoxide (DMSO) 3.96 95 78 Ethylene Glycol (EG)2.28 110 62 Propylene Glycol (PG) * 107 76

[0022] Thus, these compounds were introduced within the followingnon-limiting, but preferred and comparative examples, and analyzed andtested for various desired characteristics. Except as specificallynoted, the viscosity measurements were run on a Brookfield Viscometer at25° C. with a spindle of 6 rpm.

[0023] A. Viscosity Behavior of Various Inventive and ComparativePigment Dispersions

[0024] 1. Ferro Super Black 34-81107 Viscosity Measurements(cps) for 0,1, 3, 5, 10, and 15% by weight additions of modifier. Additive Standard1% 3% 5% 10% 15% PC 6,966 5,533 4,320 3,133 2,241 — BLO 6,966 5,6003,970 2,800 1,530 800 EC 6,966 5,700 4,520 4,550 6,350 25,320 EG 6,9666,408 7,145 7,384 8,777 11,146

[0025] Thus, propylene carbonate and butyrolactone were found to beexcellent viscosity modifiers for this particular specialized pigmentdispersion. Ethylene carbonate is a semi-solid and does not work forthis particular pigment. Ethylene glycol, however, free hydroxyl groups,is not a good viscosity modifier at all.

[0026] 2. Ferro Black 34-88111 Viscosity Measurements (cps) for 0, 3, 5,10, and 15% additions by weight of modifier: Additive Standard 3% 5% 10%15% PC 25,050 21,800 16,850 12,550 7,550

[0027] This particular pigment (not present within a low viscositydispersion) is conventional, and propylene carbonate provided excellentviscosity modifications at each level.

[0028] 3. Ferro Ester Black 33-88033 Viscosity Measurements (cps) for 0,1, 3, 5, 10, and 15% additions by weight of modifier: Additive Standard1% 3% 5% 10% 15% PC 3,000 2,900 2,640 2,120 1,880 1,220

[0029] Again, propylene carbonate provided excellent viscositymodifications.

[0030] 4. Rebus Carbon Black 1106 Viscosity Measurements (cps) for 0, 1,2, 3, 5, 10, and 15% by weight additions of modifier: Additive Standard1% 2% 3% 5% 10% 15% PC 11,200 9,250 9,000 8,400 7,700 5,350 3,750 EG11,200 11,146 10,905 10,664 9,110 4,233 2,518

[0031] At lower concentrations, PC is a much more effective viscositymodifier than EG.

[0032] 5. Rebus Black 2101 Viscosity Measurements (cps) for 0, 1, 3, 5,10, and 15% by weight additions of modifier: Additive Standard 1% 3% 5%10% 15% PC 11,900 11,350 9,800 8,400 5,400 2,200

[0033] Propylene carbonate is an excellent viscosity modifier for thisspecific pigment dispersion.

[0034] 6. Rebus High Strength Black 2125 Viscosity Measurements (cps)for 0, 1, 3, 5, 10, and 15% by weight additions of modifier: AdditiveStandard 1% 3% 5% 10% 15% PC 84,100 38,600 29,400 16,130 9,100 7,200 BLO84,100 63,660 42,800 16,740 15,500 8,690 CLO 84,100 69,800 49,450 40,46015,600 8,590 DOL 84,100 78,600 73,200 39,800 17,840 4,150

[0035] For this specific pigment (not in a liquid dispersion intially),all of these provided excellent viscosity modifying characteristics.

[0036] 7. Polyton Black UE-3012 Viscosity Measurements (cps) for 0, 1,2, 3, 5, 10, and 15% by weight additions of modifier: Additive Standard1% 2% 3% 5% 10% 15% PC 11,100 10,700 9,950 9,050 7,525 5,625 4,150 BLO11,100 10,100 — 8,300 6,887 4,125 2,475 EG 11,100 9,592 9,131 9,8018,712 8,503 8,691

[0037] Propylene carbonate and butyrolactone are much more effectiveviscosity modifiers than ethylene glycol for this specific pigmentdispersion.

[0038] 8. Union Black 5U-500 Viscosity Measurements (cps) for 0, 1, 3,5, 10, and 15% by weight additions of modifier: Additive Standard 1% 3%5% 10% 15% PC 6,700 6,180 5,950 4,600 3,200 2,180 BLO 6,700 5,980 4,7503,970 2,350 1,450 CLO 6,700 6,080 5,160 4,650 3,030 2,070 DOL 6,7005,690 4,040 3,070 1,470 810 DMSO 6,700 6,060 4,940 4,110 2,770 1,620 EG6,700 6,650 6,020 5,820 5,030 6,120

[0039] This pigment is initially present as a paste and is made fromabout 25-40% carbon black, 75-60% polyether polyol and a small amount ofother additives. The cyclic compounds such as propylene carbonate,butyrolactone, and caprolactone are excellent modifiers for thisspecific pigment. 1,3-Dioxolane and DMSO are good modifiers ofviscosity. Ethylene glycol is by far the least effective at viscosityreduction of the group.

[0040] 9. Union Black 3U-600 Viscosity Measurements (cps) for 0, 1, 3,5, 10, and 15% by weight additions of modifier: Additive Standard 1% 3%5% 10% 15% PC 8,280 7,690 6,070 4,870 3,070 1,940 BLO 8,280 7,260 5,8704,580 2,860 1,501 DOL 8,280 6,590 5,090 3,630 1,590 810 EG 8,280 8,0107,470 7,130 7,290 7,220 PG 8,280 8,70 7,220 6,590 4,500 3,520 THF 8,2806,910 4,740 3,400 1,460 650

[0041] Again, the cyclic compounds, 1,3-dioxolane, and tetrahydrofuranare good viscosity modifiers for this pigment. The glycols are poorselections for this purpose.

[0042] 10. PEKA Ether Black VP6000 Viscosity Measurements (cps) for 0,1, 3, 5, 10, and 15% by weight additions of modifier: Additive Standard1% 3% 5% 10% 15% PC 3,110 3,000 2,560 2,130 1,250 750 BLO 3,110 2,8302,530 2,170 1,320 640

[0043] Again, the cyclic modifiers were excellent for the reduction ofviscosity for this pigment.

[0044] 11. PEKA Ester Black ES 100 Viscosity Measurements (cps) for 0,1, 3, 5, 10, and 15% by weight additions of modifier: Additive Standard1% 3% 5% 10% 15% PC 7,600 6,240 5,820 5,340 2,260 390

[0045] Propylene carbonate proved to be extremely effective forviscosity reduction of this pigment.

[0046] 12. Dong Ryung Pigment Black Viscosity Measurements (cps, 2.5rpm, 25° C.) for 0, 1, 3, 5, 10, and 15% by weight additions ofmodifier: Additive Standard 1% 3% 5% 10% 15% PC 17,440 16,540 12,30012,120 6,340 4,020 BLO 17,440 16,191 10,491 9,810 7,175 5,336

[0047] The cyclic compounds again proved to reduce the viscosity of DongRyung Pigment Black dispersion effectively.

[0048] 13. Kuang Lung Black (from Taiwan) Viscosity Measurements (cps, 1rpm, 25° C.) for 0, 1, 3, 5, 10, and 15% by weight additions ofmodifier: Additive Standard 1% 3% 5% 10% 15% BLO 39,350 30,450 27,20022,550 16,700 11,000

[0049] Butyrolactone provided excellent reduction of this thick pastepigment.

[0050] 14. Rebus Green 1750 Viscosity Measurements (cps) for 0, 1, 3, 5,10, and 15% by weight additions of modifier: Additive Standard 1% 3% 5%10% 15% PC 6,216 5,566 4,966 4,035 2,750 1,875 BLO 6,216 5,541 4,6253,565 2,891 1,686

[0051] Again, the cyclic propylene carbonate and butyrolactone providedexcellent viscosity modification for this specific pigment.

[0052] 15. Ryvec Pigment Dispersions (COMPARATIVES)

[0053] a) Ryvec Blue Viscosity Measurements (cps, 25° C., 2.5 rpm) for0, 1, 2, 5, and 10% by weight additions of modifier: Additive Standard1% 2% 5% 10% PC 18,000 17,600 16,220 15,440 12,040

[0054] b) Ryvec Green Viscosity Measurements (cps) for 0, 1, and 3% byweight additions of modifier: Additive Standard 1% 3% PC 975 1,080 1,066

[0055] c) Ryvec Black Viscosity Measurements (cps, 25° C., 100 rpm) for0, 1, 3, and 5% by weight additions of modifier: Additive Standard 1% 3%5% PC 337 382 404 422

[0056] Ryvec pigment dispersions are made from pigments, fatty alcoholsor fatty esters, and naphthenic oils and are not physically stable uponsettling. Viscosity modifiers do not work in these dispersion systems.

[0057] B. Physical Stability of Inventive and Comparative Dispersions

[0058] 1. Centrifugation Test (A)—Viscosity Comparison

[0059] Procedures Followed

[0060] a) 50 g samples of inventive dispersions (Pigment/5% PC blend;47.5 g pigment dispersion with 2.5 g Propylene Carbonate) were made aswell as 50 g samples of pigment alone.

[0061] b) The samples were then tested for physical stability bycentrifugation:

[0062] i) The initial viscosity of each sample was first measured byBrookfield Viscometer.

[0063] ii) Centrifuge tubes were then filled separately to about ½ fullwith inventive and comparative dispersions.

[0064] iii) The tubes were then capped and placed within the centrifugewith the tubes balanced on opposite sides of the centrifuge.

[0065] iv) The centrifuge was then run for 15 minutes at 1300 rpm.

[0066] v) The resultant samples were then observed for separation ofcolor from the liquid.

[0067] vi) The viscosity of each centrifuged sample was then measured.

[0068] Samples Tested

[0069] The following samples were used for testing:

[0070] a) Ferro Super Black 34-81107

[0071] b) Super Black/5% PC

[0072] c) Union Black 5U-500

[0073] d) 5U-500/5% PC

[0074] e) 5U-500/10% PC

[0075] f) 3U-600/5% PC

[0076] g) 3U-600/10% PC

[0077] Results and Conclusions

[0078] In addition to visual observations, the initial and centrifugedviscosities of the samples were measured. No significant visual changesor viscosity differences were noticed. The data (25° C., 6 rpm) are asfollows: Initial Visc. Visc. after Sample (cps) Centrifugation (cps)Ferro Super Black 34-81107 6,980 7,020 Super Black/5% PC 3,230 3,280Union 5U-500 6,560 6,480 Union 5U-500/5% PC 4,220 4,210 Union 5U-500/10%PC 2,760 2,770 Union 3U-600/5% PC 4,920 4,870 Union 3U-600/10% PC 3,0803,075

[0079] Thus, all of the above inventive and comparative dispersions werephysically stable upon centrifugation test in term of viscosity, showingno deleterious effects due to reduction of viscosity utilizing theabove-noted viscosity modifiers.

[0080] 2. Centrifugation Test (B)—Foam Performance Comparison

[0081] Procedures

[0082] The same centrifuged samples were utilized to test foamperformance in order to verify the physical stability of samples aftercentrifugation:

[0083] 1 g of each sample was carefully removed from the top of each ofthe centrifuged samples and mixed [in a 1 part per hundred (php) amountof toluene diisocyanate] to produce a polyurethane foam for each sample.These foams were then compared with 1 php foams of regular uncentrifugeddispersions. The depth of shade of each sample was compared with itscentrifuged counterpart for any changes (by Hunter Color Instrument#00550, in relation to changes in lightness and darkness, ΔL)

[0084] Samples Tested

[0085] The following samples were used for testing:

[0086] a) Ferro Super Black 34-81107

[0087] b) Super Black 34-81107/5% PC

[0088] c) Union Black 5U-500

[0089] d) 5U-500/5% PC

[0090] e) 5U-500/10% PC

[0091] f) 3U-600/5% PC

[0092] g) 3U-600/10% PC

[0093] Results and Discussion

[0094] The legend for this table is: un=uncentrifuged; cent=centrifuged;ΔL* is the change in lightness (+) or darkness (−) from theuncentrifuged sample to the centrifuged sample; pass/fail concerns theacceptability of the particular L* for each specific sample. Sample FoamStrength ΔL Pass/Fail Super Black (un) 1 php 0 pass Super Black (cent) 1php ˜0 pass Super Black/5% PC (un) 1 php 0 pass Super Black/5% PC (cent)1 php ˜0 pass 5U-500 (un) 1 php 0 pass 5U-500 (cent) 1 php 1.19 pass5U-500/5% PC (un) 1 php 0 pass 5U-500/5% PC (cent) 1 php 0.53 pass5U-500/10% PC (un) 1 php 0 pass 5U-500/10% PC (cent) 1 php −0.17 pass3U-600/5% PC (un) 1 php 0 pass 3U-600/5% PC (cent) 1 php −0.84 pass3U-600/10% PC (un) 1 php 0 pass 3U-600/10% PC (cent) 1 php 1.13 marginal

[0095] The shade matching reading from Hunter Color Instrument #00550gave a “pass” or “marginal pass” to all of the above uncentrifuged andcentrifuged sample sets evincing the same physical stability results asabove.

[0096] 3. Thermostability Test (C)—50° C. Oven Test

[0097] Procedures

[0098] a) 50 g samples of an inventive dispersion [50 g of SuperBlack/5% PC blend (47.5 g Super Black, and 2.5 g Propylene Carbonate),for example] and a comparative dispersion (50 g of Super Black alone,again, as one example) were produced and placed in separate 4 ouncejars.

[0099] b) Thermo-Phase Stability Test:

[0100] i) The initial viscosities of the samples were first measured.

[0101] ii) The samples were then tightly capped and place in a 50° C.oven; the potential phase separation and viscosity of each sample wastested every two days.

[0102] Samples Tested

[0103] The following samples were tested in a 50° C. oven:

[0104] a) Ferro Super Black 34-81107

[0105] b) Super Black 34-81107/5% PC

[0106] c) Union Black 5U-500

[0107] d) 5U-500/5% PC

[0108] e) 5U-500/10% PC

[0109] Results and Discussion

[0110] Some small changes were noticed for each sample over a sustainedduration. The results (cps, 4 rpm, 25° C.) were as follows: Super Black344-81107/5% PC: Initial 2 days 4 days 8 days 10 days 14 days 16 days 21days 3,025 3,100 3,125 3,350 3,350 3,800 3,770 3,750

[0111] Union Black 5U-500 and its PC blends: 2 5 7 9 12 14 SampleInitial days days days days days days 5U-500 6,800 6,860 7,000 7,2007,160 7,300 7,450 5U-500/ 4,470 4,560 4,660 4,700 4,770 4,800 4,970 5%PC 5U-500/ 2,770 3,040 3,080 3,120 3,160 3,250 3,280 10% PC

[0112] Over the period of 2-3 weeks at 50° C., some viscosity increaseswere observed for both standard CB dispersion and its PC blends, butthese changes were insubstantial. The addition of PC as a viscositymodifier within such pigment dispersions did not cause a meaningfuldifference in terms of thermostability.

[0113] 4. Heating/gelation Test (D)

[0114] Procedure

[0115] In order to investigate whether the addition of PC causesgelation problems within pigment dispersions, the following procedureand test were performed (utilizing a Brookfield Programmable DV-II+Viscometer):

[0116] a) 9 g of a sample (an inventive dispersion and its comparablenon-viscosity modified dispersion) were placed within a viscometer cup,and set upon the viscometer.

[0117] b) The temperature was adjusted to a control of about 60° C.

[0118] c) The motor was started and the speed was adjusted to itsmaximum torque.

[0119] d) The viscosity for each sample was then read at 60 minuteintervals over 24 hours.

[0120] Samples Tested

[0121] The following dispersions were tested:

[0122] a) Ferro Super Black 34-81107

[0123] b) Union Black 5U-500

[0124] c) 5U-500/5% PC

[0125] d) 3U-600

[0126] e) 3U-600/5% PC

[0127] f) 3U-600/10% PC

[0128] Results and Discussion

[0129] The selected viscosity readings (cps, 60° C., 6 rpm) aresummarized as the following: Sam- ple 1 h 4 h 8 h 12 h 16 h 20 h 24 hSu- 1,364 1,346 1,233 1,189 1,170 1,168 1,158 per Black 5U- 1,116 1,1181,119 1,128 1,140 1,152 1,158 500 5U- 901 907 916 920 931 935 940 500/5% PC 3U- 1,269 1,303 1,333 1,351 1,380 1,407 1,423 600 3U- 863 878 897907 920 921 940 600/ 5% PC 3U- 527 529 541 545 550 556 562 600/ 10% PC

[0130] Except for Super Black, slight viscosity increases were noticedfor all of the samples tested. The addition of PC into the standardpigment dispersions did not evince any appreciable adverse viscositybehavior differences upon heating to 60° C.

[0131] 5. Freeze-thaw Test (E)

[0132] Procedure

[0133] The following procedure was followed to perform this Freeze-thawtest in a −13° C. freezer:

[0134] a) 200 g samples of inventive and comparative dispersions wereprepared in 4-oz jars and tightly capped after their initial viscositieswere measured.

[0135] b) The capped samples were then placed into a −13° C. freezer for15 h; after that period, the samples were warmed to room temperature for9 hours; then the samples were subjected to a total of three suchfreeze/thaw cycles.

[0136] c) The samples were then measured for resultant viscosities andcompared with the initial readings.

[0137] Samples Tested

[0138] The following 8 samples were tested:

[0139] a) Union 5U-500

[0140] b) 5U-500/5% PC

[0141] c) 5U-500/10% PC

[0142] d) 3U-600

[0143] e) 3U-600/5% PC

[0144] f) 3U-600/10% PC

[0145] g) Super Black 34-81107

[0146] h) Super Black 34-81107/5% PC

[0147] Results and Discussion

[0148] The results are summarized as the following: Sample Initial Visc.Final Visc. 5U-500 6,980 cps 6,450 cps 5U-500/5% PC 4,210 4,1415U-500/10% PC 2,760 2,730 3U-600/5% PC 4,920 4,870 3U-600/10% PC 3,0803,075 Super Black 6,770 6,650 Super Black/5% PC 3,100 3,040

[0149] The above data suggest that the inventive dispersions are atleast as stable as standard pigment dispersions at −13° C. The additionof PC does not destabilize the standard pigment dispersions at freezingtemperatures.

[0150] 6. Long-term Storage Stability Test (F)

[0151] The following samples were stored at room temperature for a long,specified duration. Every four days about 5 g from the top portions ofthe samples were taken from each separate bottle and measured forviscosity. The results over a course of two months are as follows: 0 1121 31 47 56 62 Sample day days days days days days days Super 3,0903,090 3,020 3,030 3,100 3,140 — B/5% PC 5U-500 6,490 6,490 6,540 6,5206,210 6,350 6,310 5U-500/ 4,220 4,130 4,260 4,180 3,990 3,960 3,980 5%PC 5U-500/ 2,760 2,850 2,900 2,720 2,420 2,430 2,640 10% PC

[0152] As the results suggest, the addition of PC does not affect thestability of standard pigment dispersions.

[0153] C. Reactivity of Preferred Low Dipole Moment Cyclic CarbonateViscosity Modifiers in During Polyurethane Foam Formation

[0154] Procedures

[0155] The following procedures were followed to perform this test:

[0156] a) 10 php black polyether foams were produced by introducingeither an inventive dispersion or a standard pigment dispersion. Theresultant foams were stored at room temperature for one week.

[0157] b) 2 g of each respective foam were then cut from the samplesabove, placed within 100 ml of MeOH at 50° C. oven for 1 hour, and thenat room temperature for 18 hours (to test for extraction).

[0158] c) After removal of the foams, 10 mL aliquots of the MeOHsolutions were then analyzed for PC presence by GC-MS in comparison witha pure 10 mL PC standard.

[0159] Samples Tested

[0160] 3 Black PE foams by using the following samples as colorationreagents at 10 php levels:

[0161] a) Union Black 3U-600

[0162] b) 3U-600/5% PC

[0163] c) 3U-600/10% PC

[0164] Results and Discussion

[0165] No propylene carbonate (PC) was detected in any of the abovemethanol extractions.

[0166] D. Build Curves for Colored Foams

[0167] Procedure

[0168] In order to compare the relative strength of standard carbonblack dispersions with their respective inventive low viscosity blends,various standard polyurethane ethyl foams (1.5 pdf density) were made at0.1, 0.5, 1.0, 2.0, 4.0, 6.0 and 10.0 php levels, by using the followingsamples:

[0169] a) Ferro Super Black 34-81107

[0170] b) Super Black 34-81107/5% PC

[0171] c) Union Black 5U-500

[0172] d) 5U-500/5% PC

[0173] e) 5U-500/10% PC

[0174] f) Union Black 3U-600

[0175] g) 3U-600/5% PC

[0176] h) 3U-600/10% PC

[0177] The coloration depth of the foams were analyzed by a Hunter ColorInstrument to determine appropriate L* values at such different colorloadings. The L* values (represent the coloration depth) were used toplot the build curves which are represented in FIGS. 1, 2, and 3. As caneasily be seen, the coloration depth provided by the low viscositycompositions are essentially the same as for the unmodified basepigments or pigments dispersions. Such a result is extremely surprisingas this connotes that the “diluted” pigments retain substantially thesame color values as the high viscosity (and thus, theoreticallystronger color) couterparts. These build curves thus represent the mostimportant discovery with this invention, in that no loss of colorstrength is created upon viscosity reduction with utilization of thevery favorable low dipole moment or specific low flash point viscositymodifying agents within pigment compositions.

[0178] While the invention will be described and disclosed in connectionwith certain preferred embodiments and practices, it is in no wayintended to limit the invention to those specific embodiments, rather itis intended to cover equivalent structures structural equivalents andall alternative embodiments and modifications as may be defined by thescope of the appended claims and equivalence thereto.

What we claim is:
 1. A method of producing a colored polyurethanecomprising the steps of (a) providing a polyol composition; (b)introducing a nonaqueous liquid dispersion comprising at least onepigment and at least one aprotic viscosity modifying compound exhibitinga dipole moment of between about 1.0 and 5.0 or, alternatively,exhibiting a flash point of between about −20° C. and 180° C. into saidpolyol composition to form a colored polyol composition; and (c) mixingsaid colored polyol composition with an isocyanate to form apolyurethane.
 2. The method of claim 1 wherein said at least one aproticviscosity modifying compound is a liquid possessing a viscosity of atmost 500 centipoise at standard temperature and pressure, and whereinsaid viscosity modifying compound does not possess any constituenthydroxyl, amine, or acid groups.
 3. The method of claim 1 wherein saidat least one aprotic viscosity modifying compound possesses an averagemolecular weight of at most
 300. 4. The method of claim 1 wherein theviscosity of said dispersion is at most 5,000 centipoise at standardtemperature and pressure.
 5. The method of claim 1, wherein said atleast one viscosity modifier is selected from the group consisting of atleast one cyclic carbonate, at least one dioxolane, and any mixturesthereof.
 6. The method of claim 5 wherein said at least one viscositymodifier is selected from the group consisting of at least one cycliccarbonate.
 7. The method of claim 6 wherein said at least one viscositymodifying compound is propylene carbonate.
 8. A method of producing acolored polyurethane comprising the steps of (a) providing a polyolcomposition; (b) introducing a nonaqueous liquid dispersion comprisingat least one carbon black pigment and at least one aprotic viscositymodifying compound exhibiting a dipole moment of between about 1.0 and5.0 or, alternatively, exhibiting a flash point of between about −20° C.and 180° C. into said polyol composition to form a colored polyolcomposition; and (c) mixing said colored polyol composition with anisocyanate to form a polyurethane.